I just realized how incredible it is that we don't have toes growing out of our ears.
AFAIK it all boils down to the fact that during embryonal development our cells, which at that point were just a blob of undifferentiated autonomous chemical machines, somehow managed to unanimously agree upon the cardinal directions (up-down, left-right, front-back) for future development - and thanks to this, we don't have toes growing out of our ears.
I mean, that's what dna is for. These machines aren't operating blindly (or even "cooperating" or agreeing on anything, really). They're following the code that makes up who we are.
They don't so much know where they are as much as they're just interacting with what's there in the way they were made to, which was all put there due to the DNA to function as a whole.
And to be clear, it's all still amazing, just in a different way. Here's Kurzgesagt video that helps explain how these cells "communicate" to do things like put a body together in the right order.
Someone was probably born with toes on their head in the past and life didn't go so well that they could have children that also survived. This is why our DNA doesn't have instructions for growing toes on our head.
If an embryo decides to split in two, and then sends out the marker that "this is the right side" and it's too close to the other embro, there will be a set of identical twins, but one will have the heart on the right side, appendix on the opposite side etc. This needs to be known if the "mirrored" person has a colonoscopy, since the colon is folded the opposite direction.
Too bad evolution is blind, and now our windpipes and digestive tracts cross over. It works, but it would have been nice if choking wasn't a thing.
Other examples of interesting (sometimes called 'unintelligent') evolution might be how we walk upright, leading to complications with childbirth and back pain, blindspots because of our optical nerve, and or that recurrent nerve that does a random U-turn.
Evolution is basically millions of years of patches without ever getting a rebuild form the ground up. It's mostly ok, but some bugs stick around
Interestingly, the recurrent laryngeal nerve is looped around that way because the structure of the nerve grows in before the structures of the aorta and other large vessels fully grow in and orient into their correct position, so the nerve ends up looping around them.
This is just based on an offhand comment from a lecturer during a practical session during my time studying animal management in college, not directly from a biology lecturer so citation needed, but apparently rabbits don't have a combined windpipe/digestive tract and it means that a blocked nose can kill them. So even if choking wasn't a thing we'd have to worry about something blocking our noses and suffocating us.
I always thought that was a poor design. Aliens likely would find that disgusting.
What interests me is that I believe all warm blooded animals also share this trait. Not certain that is true but if so, wouldn't that mean it evolved in a very early period?
Also what I find interesting is that the layout of humans to most animals is the same. A head with eyes then nose then mouth among with the brain behind it. Most of the organs are in similar locations. It seems strange that there would not be more variety.
I can't comment on anyone with toes out of their ears, but I've seen a lot people with their butt where their face is. Or at least it would appear so, as a lot of shit seems to come out of the hole in their face.
That's why there is an entire community for shower thoughts: because people sometimes get these sudden realizations. But honestly, you got me - I realized it a few days ago and only got around to post it "now".